CSJ ■■-■• - ... — --.T— ^J- 'jf' g ^^ ?i! I CD y .= _,^ v^ :'W o -^ jy^B (3 ■> ?■ ^?r(^ ^ ^r- -^^= ' 1 ' ,i ) ;* CO Lawson, Andrew Cowper The geology of Steeprock lake CANADA DEPARTMENT OF MINES GEOIiOGICAI, SUBVEY BRANCH Hon. W. B. Nantel, Minister; A. P. Low, Deputy Minister; K. W. Brock, J^iiiEcroi;. MEMOIR No. 28 Andrew C. Lawson. NOTES ON FOSSILS FROM LIMESTONE OF STEEPROCK LAKE, ONTARIO Charles D. Waloott. OTTAWA WOVERNMBNT PRINTING BUREAU 1912 No. 1213 16279-1 Qb I ^ I LETTEK OF TRANSMITTAL. E. W. Brock, Esq., Director Geological Survey, Department of Mines, Ottawa. Sir, — I beg to submit herewith a memoir on the geology of Steeprock lake, Ontario ; together with notes by the Hon. Charles D. Walcott, on certain fossils found in the limestone of the same area, which have a peculiar interest in that they are apparently the oldest forms of life yet discovered. I have the honour to be, sir. Tour obedient servant. (Signed) Andrew C. Lawson. 16279-2 TABLE OF CONTENTS. Page. Geology of Steeproek lake, Out., by Andrew C. Lawson 7 Notes on fossils from lime|tone of Steeproek lake, Ont., by Charles D. Walcott 16. ILLUSTEATIONS. Plate I, figs. 1-5 — Aiikokania lawsoni Walcott 21 " II, fig. 1 — Atikol-ania irregularis Walcott 23 " 2 — Atikokania lawsoni Walcott 23 " 3 — Cryptozoanl'i. sp. undt 23 1G279 -2k THE GEOLOGY OF STEEPROCK LAKE, ONT. BY Andrew C. Lawson. lu the year 1891, Mr. H. L. Smyth published an interesting paper' on the geology of Steeprock lake, in which he classified the rocks there exposed into three principal groups : — (1) The Basement Complex, consisting of granites and gneisses which typically are medium grained, hornblendie and granitoid with faint foliation. Locally they present considerable variations in composition and very great variations in structure. (2) The Steeprock series, showing a thickness of 5,000 feet. (3) The Atikokan series, a succession of later granitoid porphy- ries and massive hornblende rocks. The Steeprock series rests unconformably upon the basement complex, and is subdivided into nine formations, according to the following scheme, arranged in ascending sequence : — I. Conglomerate. II. Lower limestone. III. Ferruginous formation. IV. Interbedded ery.stalline traps. V. Upper calcareous green schist. VI. Upper conglomerate. VII. Greenstones and .creenstone schists. VIII. Agglomerate. IX. Dark grey clay slate. The sequence of these formations and their structural relations formed the chief subject matter of Mr. Smyth's paper, and the discussion of his third division, the Atikokan series, was deferred. The paper was not only interesting, but it was important from a general point of view as an announcement and description of a » Structural Geology of Steeprock lake, Ontario, Am. Jour. Sc. XLII, 1891. Y 8 GEOLOGICAL SURVEY, CANADA. series of rocks hitherto unrecognized in the Arclisean of that part of Canada. This fact has attracted a number of geologists to Steep- rock lake, and several references to the series are to be found in the literature of the region. The general question raised in all of these is the relation of the Steeprock series to the Keewatin. Smyth made perfectly clear that the Steeprock series rested uncon- formably upon his basement complex with a basal conglomerate reposing upon an eroded surface. But in that basement complex he recognized no Keewatin, but only those granites and gneisses which are usually referred to as Laurentian. The areal limits of the Steeprock series to the south and southwest were left unde- fined. In these directions, however, the rocks of the series are continuous with and indistinguishable from the Keewatin, and to any geologist who became familiar with this fact the whole implica- tion of Smyth's interpretation of the geology was that the series was in part a local facies of the Keewatin and in part a normal facies, and that the Keewatin was, therefore, unconformable upon rocks of the Laurentian type and habitus. Mr. W. H. C. Smyth,' after an examination of the series, accepted Smyth's descriptions and classification, saying : ' The work done by the writer in connexion with the rocks of this series suggests no important modification of them.' But he expressed the opinion that the Steeprock series was later than the Keewatin; a question upon which H. L. Smyth was silent. He did not, however, locate the contact of the Steeprock and Keewatin : ' The unconformity above the Keewatin schists of the Seine river to the southwest is not at all obvious. Lithologically the green traps and schists of the two series are strikingly similar and could not probably be separated by the most careful study.' Coleman,^ in 1897, regarded the Steeprock series as part of the Keewatin. He says : ' The water-formed elastics of the Kee- watin are of great variety, including limestones, quartzites, slates, grits, graywackes, breccias, and pebble and boulder conglomerates. The limestones are, however, of limited extent, being found in any thickness only at Steeprock lake, 70 miles east of Rainy lake, where there is a small area differing both petrographically and structurally from the rest of the region. These limestones have a 1 BtoII. G.S.A., Vol. 4, 1893, pp. 34i.347. 2 Bull. G.S.A., Vol. 9, p. 225. Also Eept. Bureau of Min«s, Ontario, Vol. VII, Pt. II, 1898, p. 152. GEOLOGY OF STEEPROCK LAKE. 9 very modern look, being scarcely at all crystalline in appearance, having cherty layers in grey limestone at some points and black, very carbonaceous beds at others. One almost expects to discover fossils in them, but none have been found.' He makes no dissent from the ninefold subdivision of the series proposed by Smyth, and accepts the latter's interpretation of the structure. Ifclnnes,' in 1899, accepts Smyth's ninefold subdivision of the Steeprock series, and classifies the j-ocks of the series with the Keewatin as forming the upper division of the latter; although they are believed to be of later age than the great bulk of the Kee- watin strata. In 1911, Van Hise and Leith' give a summary statement of the geology of Steeprock lake, in which the Steeprock series is correlated with the lower Huronian, and is said to rest unconform- ably upon the Laurentian and Keewatin. But the series is said to be principally exposed on the south and west shores of the lake, where, as a matter of fact, the rocks are nearly all Keewatin, so that it is evident that the areal disU-ibution of the series given by Smyth is accepted, the unconformity upon the Keewatin being inferred from the presence of Keewatin pebbles in the basal conglomerate. Smyth's ninefold subdivision of the series is quoted; but ' Some of the greenstones and greenstone schists included by Smyth in the lower Huronian are regarded by the authors as, at least in part, Keewatin.' During the past summer I took occasion to spend a few days at Steeprock lake for the purpose of acquainting myself with some of the features described by Smjrth, and for my guidance I had a copy of his paper, and the map that accompanies it. As a result of my visit, I am happily able to confirm the most important part of his conclusions, particularly as to the existence of the series as a distinct member of the Archssan, and its unconformable relation to a granite-gneiss of the basement complex. On the other hand, the observations that I made, while by no means exhausting the field, compel me to place an interpretation upon the stratigraphy and structure quite different from that of Smyth, and enable me to clear up the question of the relation of the series to the Keewatin, p. 1-17. ^Geological Survey, Canada, Ann. Report, Vol. X, Pt. H. 2 The Geology of the Lake Superior Region, U.S.G.S. Mon. LII, 1911, 10 GEOLOGICAL SURVEY, CANADA. the latter being a large part of the basement upon wliioh the Steep- rock series was unconformably deposited. I approached Steeprock lake from the west, coming up the Seine river from Eainy lake. In doing so I traced out nearly con- tinuously the geological boundary between the Keewatin of Eainy lake and a series of quartzites and slates which for convenient reference I shall here call the Seine series. The Seine series lies to the south of the Keewatin, and is post-Keewatin in age. The contact between the two series is marked not only by the striking contrast in the general character and physical appearance of the rocks, but also by the occurrence of several lenses of conglomerate, of which the most important is that of Shoal lake. To the south of the quartzites and slates are the mica schists of the Coutchiching series. The relations of the Seine and Coutchiching series will not here he discussed. It was my expectation in following the basal conglomerates of the Seine series eastward, that they would prove to be the same as one of the conglomerates described by Smyth on Steeprock lake. This expectation was, however, not realized. The boundary line between the Keewatin and the Seine series was followed with a steady E.-W. strike along the Atikokan river as far as the iron mines east of Sabawe lake. The east and west strike of the base of the Seine series is transverse to the more nearly N.W.-S.E. folds, which have involved the Steeprock series in vertical attitudes a little to the north of the Atikokan river. This stratigraphic and structural relationship indicates that the folding which involved the Steep- rock series as a sharp trough sunk down into the older Archaean had taken place anterior to the deposition of the Seine series ; since no such folding affects the even trend of the strike of the latter. It is, therefore, inferred tentatively that the Steeprock series is older than the Seine series, an inference which should be confirmed by a careful search in the conglomerates of the Atikokan river for pebbles of the Steeprock series. To the south of Sabawe lake the Seine series is cut by the granite gneiss which forms so large a j'eature of the geology of the Seine River and Shebandowan sheets. "^he phenomena of intrusion and the metamorphism of the Seine series consequent upon the intrusion are splendidly exemplified. No one who is at all familiar with the geology of the Thunder Bay district will question the unconformable superposition of the Animikie upon the complex of which this granite gneiss forms a GEOLOGY OF STEEPROCK LAKE. 11 part. From the foregoing statements, we arrive at the probable position of the Steeprock series in the geological scale; and this may conveniently be presented in the form of a tabulation in chronological sequence : — ■ ^10 Keweenawan. Algonkian ..,...-[ Erosion internal. I 9 Anin.ikie. EPARCHEAN INTERVAL. f 8 Granite gneiss, intrusive in the Seine series. Imiptive contact. I 7 Seine series. j 6 Acute deforifiation and eiosion interval. ArhiPan J 5 Steeprock series. ^-"'^'*" ^ 4 ^ Erosion interval. 3 Granite gneiss, intrusive in the Keewatiti. Irruptive contact. I 2 Keewatin. L 1 Coutchiohing. The position of the Steeprock series, well down in the Arclisean, is of interest from a general point of view, since, as will appear in the sequel, the limestone of which it is chiefly composed is fossiliferous. The fossils appear to be the oldest forms of life as yet discovered. Before proceeding with the statement of the observations which necessitate a change in the interpretation of the geology of Steep- rock lake, it may be said that the exposure of the rocks about the lake is probably much better than it was at the time of Smyth's visit in 1891. The region has been extensively, and in places very thoroughly denuded of its forests by fires, so that one may waU^ inland from the shores of the lake at many localities over bare glaciated rock surfaces. Smyth's observations were confined to the shores of the lake, and his mapped distribution of the formations away from there was conjectural, as was generally the case with maps made at that period in the Archaean terraues of western Ontario. His observations as to the extent and distribution of the two most important members of the Steeprock series : I, the basal conglomerate, and, II, the limestone about the shores of the lake, appear to have been most careful and accurate. The only modifica- tion which I was able to make in his mapping of these formations on the actual shore line was the extension of the conglomerate (I) to the main shore on the northeast side of Northwest bay. I also found no evidence of the fault which he places through Birch point. Inland from the lake shore, however, I found the distribution of th& rocks in certain localities, which are decisive for the inter- pretation of the structure, to be otherwise than Smyth had con- 16279—3 12 GEOLOGICAL SUR\'EY, CANADA. jectured. This is notably the case, for example, in regard to his formation IX — described as a dark grey clay slate. An east and west section across the peninsula which terminates in Jackpine point, made from the shore about three-fourths of a mile south of that point, showed clearly that no such formation exists as mapped. The rocks in the area mapped as clay slate are coarse agglomerate schists, cut by great dykes of greenstone. The surface here is particularly open and well exposed, and one may walk freely over the bare rocks. The supposed clay slates which crop out on the shore at Smyth's locality 81, appear to be a local facies of the agglomerate formation particularly well sheared, and having a very limited distribution at and close to the shore, and grading into the agglomerate. Formation IX, as distinct from VIII, appears, there- fore, to be non-existent; and the syncline which is based upon the supposed distribution of clay slate and agglomerate can no longer claim recognition. Tlie agglomerate VIII, and the belt of greenstones and green- stone schists VII — which lies to the east of it — are typical Kee- watin formations, indistinguishable from and continuous with the belt of Keewatin rocks of the north side of the Seine river which has been traced through from Eainy lake. To the east of the belt of greenstones and greenstone schists VII, is a narrow belt of con- glomerate— Smyth's ' Upper conglomerate ' VI. This conglomer- ate was conjecturally, but approximately correctly, mapped by Smyth. I have confirmed his mapping by tracing the conglomerate through from its outcrop on the end of the peninsula west of East bay to the south end of Straw Hat lake. This lake was evidently unknown to Smyth, although the exposures on its shores are of the utmost importance for the interpretation of the structure. It lies parallel to East bay, two-fifths of a mile west of its south end. The course of the conglomerate belt for the distance indicated is parallel to that of Smyth's conglomerate I, on the east side of East bay. East of the conglomerate is a limestone, which occupies for the most part a depression extending through from Falls bay to the south end of Straw Hat lake. The limestone is exposed at both ends of Straw Hat lake, and is identical in character with the limestone on the east side of East bay, Smyth's formation II. It evidently underlies the waters of the lake. Between the north end of Straw Hat lake and Falls bay it is exposed at intervals, and numerous blocks of it occur in the depression. The depression ends in a little GEOLOGY OF STEEPROCK LAKE. 13 bay where a small creek flows into Falls bay. To tbe west of the creek is a carbonated green schist lying against the conglomerate. This is Smyth's formation V — the ' Upper calcareous green schist.' This is probably a local impure facies of the limestone or detrital material that has been carbonated by reason of its proximity to the limestone. On a small island on the east side of Straw Hat lake the rock consists of a comparatively little altered volcanic ash which is identical with Smyth's formation III on the west side of East bay of Steeprock lake, which he refers to as a 'ferruginous formation,' but describes as an impure volcanic ash. It is a soft rock, prone to disintegration, and like the limestone, lies chiefly beneath the waters of Straw Hat lake and in the depression which extends through from Straw Hat lake to Falls bay. Between these two occurrences of the volcanic ash, the one on East bay and the other on Straw Hat lake, lies Smyth's formation TV, ' Interbedded Crystalline traps.' This I found to consist very largely of rather massive green schists of detrital origin, with abundant angular fragments of quartz, traversed parallel to the strike by what appeared to be great dykes of diabase, but which may possibly be massive flows. On the east side of East bay the fonuations are as Smyth described and mapped them, viz. : a basal conglomerate, I, of quite moderate thickness, resting on the granite gneiss of the east shore, followed to the west by bedded limestone, II, for a thickness of several hundred feet, the whole in nearly vertical attitudes. From the facts above stated, it is evident that in a section transverse to East bay and Straw Hat lake we have to deal with a twofold repetition of the same set of beds; and the unavoidable conclusion is that the structure is a simple, closely folded syncline. The three lowest formations of the Steeprock series as described by Smyth on East bay are repeated on Straw Hat lake in reverse order. The duplication of formation IV has not been made out, and it is doubtful if it can be, owing to the character of the rocks, which renders it difficult to distinguish one horizon from another, and to the dykes which cut it. The conglomerate VI is, therefore, the same as I, and it is a basal conglomerate resting upon the Keewatin. This conglomerate was deposited upon an eroded surface across the contact of the Keewatin and the granite gneiss. The insunken syncline happens to cover the contact, so that on one limb 16279— 3i 14 GEOLOGICAL SURVEY, CANADA. of the syucline the conglomerate rests upon the granite gneiss and on the other limb, upon the Keewatin. This interpretation of the structure greatly simplifies the geology of Steeprock lake. The Steeprock series is reduced to four forma- tions, viz. : Smyth's I, II, III, and IV. Formation V is identified with II, and VI with I. Formations VII and VIII are Keewatin below the basal conglomerate, and IX is non-existent as mapped. With reference to the dykes which traverse the region, it may be said that the greenstone pebbles in the basal conglomerate, which Smyth supposed to have been derived from an earlier system of dykes, are derived from the Keewatin, and that nearly all the dykes belong to his second class, i.e., are later than the Steeprock series. A word in regard to the Atikokan series also may not be out of place. I examined, very cursorily, the shores of Margaret lake, and found no reason to segregate the rocks there exposed from those of the basement upon which the Steeprock series rests. Mr. Smyth regards these rocks as of later age than the Steeprock series lying across the edges of the latter. It seemed to me that following the Steeprock formations southerly along their strike they abutted upon the rocks of Margaret lake by reason of a N.E.-S.W. fault with resultant down-throw on the N.W. side; the formations of the Steep- rock series having been entirely removed on the south side. The simplification of the structure, and the reduction of the number of its constituent formations detracts nothing, however, from the interest attaching to the Steeprock series. There is enough of it left to make it a most important member of the Archsean Complex. The fact that it is definitely segregated from the Keewatin, only adds to the interest. But perhaps the most interesting fact connected with this series is that its dominant formation, the limestone, which is estimated by Smyth to be not less than 500 feet, nor more than 700 feet in thickness, is fossiliferous. The rock is, in part, almost an aggregate of fossils, but, in part, it is also composed of calcareous detritus derived from the waste of organisms, as may be clearly determined from the cross-bedded structures which are quite apparent in it. In part the fossils are wholly calcareous, and in part they are wholly silicified, and there are intermediate conditions due to partial silicification. Where not silicified the fossils appear on the weathered surface of the limestone as radial structures, the rays extending out to a limit which is approximately circular in sections GEOLOGY OF STEEPROCK LAKE. 15 normal to the axis of the organisms. In oblique sections the peri- phery may be more or less elliptical. The diameter of these circular boundaries varies in the hundreds of specimens observed, from about 1 inch to about 15 inches. This variation in size is probably due partly to differences in the stage of development of the organism, and partly to the position of the random section of the surface of the limestone exposing the form. For when viewed in three dimen- sions and not merely in section, some of these fossils appear to have a tapering and more or less curved or- cornucopia shape. The radial structure is due to the presence of rays which diverge from the axis of the cornucopia. Occasionally, it may be observed that these are interrupted by one or m.ore cylindrical or conical septa concentric with the axis of the cornucopia, but in most cases no such concen- tric septa can be detected In other cases, particularly in regard to the larger forms, it cannot be observed that they are cornucopia shaped, an'! the rays appear to radiate in all directions from a centre. Often these fossils are so crowded together that they abut one against another; but in no case are the individual rays observed to cross. In the larger fomis the limits of the radial structure are much less definite than in the case of the smaller cornucopia shaped forms, and on the weathered surface the rays appear to fade away into the general matrix of limestone. The clearly apparent structure is, however, contained within a circular area on the surface of the rock. Where these forms have been silicified they commonly project prominently above the surface of the limestone, and the structure can be more easily observed. In these silicified forms the rays and the tapering or cornucopia shape are commonly apparent. It is evident from the sudden passage from conglomerate to limestone and from the cross-bedded character of some of the limestone, that the organisms which contributed their remains to the building up of this important formation thrived in shallow water, and that the accumulation of their structures gave rise to some sort of a fringing reef along the shore, which from time to time was reduced by the waves to a calcareous sand which was scoured by the currents. The fossils collected were submitted for study to the Hon. Charles D. Walcott, the eminent authority on the earliest forms of life, and he has very kindly supplied the descriptive notes which follow. NOTES ON FOSSILS FROM LIMESTONE OF STEEPROCK SERIES, ONTARIO,' CANADA. BY Charles D. Walcott. Through the courtesy of Dr. Andrew C. Lawson, I have had the opportunity of studying some organic remains occurring in the Steeprock series of Steeprock lake, northwest of Atikokan, on the Canadian Northern railway, west of Port Arthur, Ontario, Canada.' Mr. H. L. Smyth concluded from his studies that the Steep- rock series rested unconformably upon a basement complex, and Van Hise and Leith, in their great memoir on the Geology of the Lake Superior Eegiou, have included the Steeprock series of Smyth in the lower Huronian." The Steeprock Lake region was studied by Dr. Lawson during the season of 1911, who found in the lower limestone above the conglomerate of the Steeprock series the remains of fossils des- cribed in these notes; and from his field observations placed the Steeprock series above an erosion interval beneath which occurs the Keewatin of the Archaean. After a preliminary study of the material, I was inclined to the view that the remains indicated the presence of the Archo'o- cyathince' of the lower Cambrian; but after making thin sections and treating the silicified specimens with acid, I decided that they 1 Presented to tlie Geological Society of America, December 28, 1911, by permission of tlie Director of the Geological Survey, Canada. 2, Structural Geology of Steeprock lake, Ontario, by Henry Lloyd Smyth. American Jonr. Sci., Vol. XLII, 1891, pp. 317-331, PI. XI. ' The Geology of the Lake Superior Region. Monogr. U.S. Geol. Surv., Vol. 52, 1911, p. 148. * For definition of this family and review of the Archwocyathinse, con- sult memoir by Wm. T. Griffith Taylor, " ATchwocyathinee from the Cam- brian of South Australia." Mem. Royal Soc. South Australia, Vol. 2, PI. 2, 1910. It is unfortunate that in this otherwise very full memoir there is no reference to the genera and species noted and illustrated in the Tenth Annual Report of the U. S. Geol. Surv., 1891, pp. 599-602, Pis. 50-55. GEOLOGY OF STEEPROCK LAKE. 17 represented a group of organisms related to the sponges, or possibly to forms possessing characters of both the sponges and ArcHwo- cyathince. The central cavity, radiating tubes, and general form of Atiko- Jcania lawsoni (PI. 1, figs. 1-5), recall at once the lower Cambrian genus Syringocnema of Taylor.' In each there is a cylindrical inner cavity, an outer and inner wall with radiating tubes connecting them; the tube walls are perforate in Syringocnema, and they appear to be so in Atikokariia. The- presence of irregular septa in Atihokania serves to distinguish the genus from Syringocnema, and to cause a comparison to be made with irregularly septate genera of the ArclicBocyaUiinw, such as Pycnoidocyathus Taylor (PI. XII, fig. 68), and Sprirocyathus irregularis Taylor (PI. XVI, figs. 93 and 94).' A second and possibly a third species of AtUcokania is associated with A. lawsoni. If the interpretation of the stratigraphic position of these inter- esting fossils is correct they are probably older than the Pre- Cambrian Beltina fauna of Montana' and quite unlike it; with the possible exception of a fragment (PI. II, fig. 3) that suggests Crytozoan f occidentale.' The genus AtilcoTcania has more of a Cambrian aspect than we should expect to find in a very ancient Pre-Cambrian fauna. The Archwocyathince are of late lower Cam- brian age, and if the stratigraphic position were not well determined I should be inclined to consider Atikohania as a lower Cambrian genus. DESCRIPTION OF FOSSILS. Genus ATiKOK.iNiA, new genus. General form cylindrical, pear-shaped or somewhat irregularly elongated, semi-globose. Central cavity more or less cylindrical and of varied form and proportions. ^Valls. — The outer and inner walls are more or less well-defined, and they are united by a series of small, more or less hexagonal iLoc. cit., p. 153, PI. 14. 2 Loc. cit. Footnotes 1, preceding page, and 1, above. 'Pre-Cambrian Fossiliferous Formations, Walcott. Bull. Geol. Soc. America. Vol. 10, 1899, pp. 235-239. *Loc. cit., p. 233. PI. XXIII, figs. 1-4. 18 GEOLOGICAL SURVEY, CANADA. tubes that radiate outward and upward at varying angles. The walls of the radial tubes are perforate, and divided by more or less irregular incomplete septa. Orowth. — The mode of growth appears to have been essentially the same as that of Archaocyatliincp, where individuals press against each other that appear to have united at the point of contact by a more or less confused compact growth. Affinities. — For the present and awaiting larger collections and possibly much better material, a relation may be assumed with the Porifera on the one hand and the Arclmocyatlmioe on the other, with a strong tendency towards the first. Ohservaiions. — There are two species now referred to the genus: A. lawsoni, n. sp., and A. irregularis, n. sp. One or two other species are indicated, but the material is not sufficiently complete for specific description. Genotype. — Atilohania lawsoni, n. sp. Atikokama lawsosi, n. sp. (PI. I, figs. 1-5 ; PL II, fig. 2.) The general form of this species is elongate conical or cylin- drical as far as can be determined from several fragmentary specimens. Central cylindrical cavity relatively small and expand- ing towards the upper outer portion of the central cavity. Walls. — The outer and inner walls are fairly well defined, but owing to the condition of preservation none of their details of structure are preserved. Tubes.— The walls of the tubes are pressed one against the other so as to form a practically solid mass of tubes that have a more or less hexagonal outline. The tubes are so arranged in the cylindrical specimens that they radiate like the spokes of a wheel from the inner to the outer walls and increase in number by inter- polation of additional tubes. In one vertical section (fig. 1, PL I) the tubes rise from the inner wall with a slope of about 10°-15°. In other sections the slope is greater. The tubes vary in size from a sharp elongate point where they start between other tubes to 2 mm. in diameter at their outer end. S'epio.— Incomplete, irregular septa occur in the tubes at irregular distances. GEOLOGY OF STEEPROCK LAKE. 19 Pores. — Pores appear in the walls between the tubes, but none have been seen in either the inner or outer wall. Exoihccal Groivth. — The presence of e.xotheeal tissue somewhat similar to that so common in Arcluvocyaihus is suggested by some specimens, but it is not sufficiently clear to warrant giving it as a character of the genus or species. Growth. — The mode of growth appears to have been individual, although, as illustrated by fig. 5, PI. I, two central cavities appear in what would otherwise have been" considered an individual. The radial tubes are more or less confused where those that radiate from the two cavities come in contact. My present impression is that the two grew side by side, with only a very slight distance between them, when small; as they grew, the central cavities were crowded farther apart. Formation and Locality. — Limestone of Steeprock series, Steep- rock lake, west-northwest of Lake Superior, Ontario, Canada. Atikokaxia irregularis, .\. SP. (PI. n. Fig. 1.) The specimen representing this species is a weathered, oblique section, 6-5 cm. in height and 11 cm. in width. The radiating tubes are more irregular and smaller than those of A. lawsoni, and the general appearance of the specimen is more like that of a portion of a large semi-globular sponge. A second frag-ment that may be referred to this species indi- cates that the central cavity was very small. This species is associated in the same limestone with A. lawsoni. 20 DESCRIPTION OF PLATE I. Page. Atikokanu lawsoni Walcott 21 Fig. 1. — Natural size. A naturally -weathered cylinder or pil>© that is silicified in its limestone matrix. This shows quite clearly the central cavity at the summit, also where it is cut across below by the erosion of the specimen. U.S. National Museum, Catalogue No. 58313. Geological Survey, Canada, CataloRue No. 8059a. " 2. — Enlargement x 6. of a portion of the weathered section in Fip;. 1, which shows the walls of the tubes with pores at a, also somewhat irregular septa crossing the tubes. " 3. — Enlargement x 3, of the upper surface of Fig. 1. 4. — Natural size. A weathered specimen where erosion has worn down into the central cavity. U.S. National Museum, Catalogue No. 5831-1. Geological Survey, Canada, Catalogue No. 8059b. 5. — Natural size. An oblique transverse section, cutting across the central cavities of two individuals that occur side by side. U.S. National Museum, Cata- logue No. 58315. Geological Survey, Canada, Cat- alogue No. 80>9c. 21 Plate I. P^igs. 1-5. Atikokama i.awsu.m Walcott. 2S DESCRIPTIOX OF PLATE II. Page. Atikokanu ip.eegulaeis, Walcott 23 Fig. 1. — Natural size. A weathered section, showing irregailar tubes radiating from what was probahly a portion of the central cavity. U.S. National Museum, Cata- logue No. 58317. Geological Survev, Canada, Cat- alogue No. 8059d. Atikokania LAwsONi Walcott 23 Fig. 2.— Natural size. Polished section of a piece of limestone where the radiating tubes are cut across, at difierent angles. The sections of the tubes on the right half are nearly at right angles to the tubes, while those on the left are more or less oblique. All of the sections of the tubes appear to baye been more or less disturbed by the compression of the limestone in which they are embedded. U.S. National Museum, Catalogue No. .58316. Geological Survey, Canada, Catalogue No. 8059e. Cryptozoan ?? sp. undt 2.3 Fig. 3. — Natural size. Photograph of a thin section of what may be a form allied to the Prc-Cambrian Crypto- zoan of the Grand Canyon section of Arizona. U.S. National Museum, Catalogue No. 58318. Geological Survey, Canada, Catalogue No. 8059^ 23 Plate II. '\' *r-^%A? Fig. 1. Atikokania ikregllaris Walcott. " 2. .. LAWSOM Walcott. " 3. Cryptozoan T: sji. nndt CANADA DEPARTMENT OF MINES GEOLOGICAI, SUKVEY BRANCH Hon. W. B. Nantel, Minister; A. 1'. Low, R. W. Brock, Dihectok. Deputy Minister ; SELECTED LIST OF REPORTS AND MAPS (SINCE 1885) OF SPECIAL ECONOMIC INTEREST PUBLISHED BY THE GEOX.OG1CAL, SURVKY. Report of the Mines Section: — No. 245. Keport of Mines Section, 1886. No. 662. Report of Mines Section, 1897 272 -■W. I. W- ^^1**. ^^ 1887. 698 1898 *300 • 1888. 718 1899 301 . .< 1«89. 744 1900 334 < it 1890. 800 1901 335 • n 1891. 835 190e 360 ., 1892. 893 1903 572 , « 1893-4 •928 1904 602 ' " 1895. 971 1905 625 t " 1896. Mineral I 'rodnction ol Canada:— No. *41l. "i 'ear 1886. No . *422. Year 1«93. No. 719. Year 1900. *415 " 1887. *55o " 1834. 718a ■' 1901. '116 " l«g8. •577 " 1895. 813 " 1902. *417 " 1889. •612 " 1896. 861 " 1903. *«8 " 1890. •623 " 1886-96. 896 " 1904. *4.19 " 1891. *640 " 11897. 9-24 " 1905. *420 " 1886-91. •671 " 1S98. 981 " 1906. •421 " 189:'. •686 " 1899. ■ Mineral ] Resources Bnlletin; — No. *S18. I 'latinum. No. 860. Zinc. No. 881. Phosphate. 851. ( ^oal. 869. Mica. 882. Copper. *8.>1. . Vsbestos. 872. Molybdenum 913. Mineral Pig- 857. ] nfusorial and Tungsten. ments. Earth. •877. Graphite. 953. Barytes. 858. 1 \Ianganese. 880. Peat. 984. Mineral Pig- 859. i Salt. ments (French). Report oi E tie Section of Chemistry and Mineralogy:— No. *102. ' rear 1874-5. No. *ica. Year 18S2-3-4 No. 580. Year 1894. *110 ■' 1875-6. 2*2 " 1885. 616 " 1896. •119 " 1876-7. aie " 1SS6. 651 " 1896. *126 " 1877-8. 273 " 1887-8. 695 " 1898. *138 " 1878-^. 299 " 1888-9. 721 " 1899. •148 " 1879-80. 333 •■ 1890-1. 821 " 1900. •150 " 1880-1-2. 359 ■• 1S92-3. •958 " 1906. * Publications marked thus are out of print. REPORTS. GENERAL. 745. Altitudes of Canada, by .T. White. 1899. t, . . t i t •972. Descriptive Catalogue of Minerals and Rocks, by K. A. A. .lohnston and G. A. Youns. 1073 Catalogue of Publications: Reports and Mans (1843-1909). 1085. Descriptive Sk'etch of the Geology and Ecouoniic Minerals of Canada, by G. A. Young, and Introductory by E. W. Brock. Maps No. 1084; No. 1042 (>econd edition), scale 100 m. = 1 m. 1086 Trench translation of Descriptive Sketch of the Geology and Economic Minerals of Canada, by G. A. Young, and Introduc- tory by R. W. Brock. Maps No. 1064; No. 1042 (second edition), scale 100 m. = 1 in. ., , , , .. 1107 Part II. Geological position and character of the oil-shale deposits of Canada, by R. W. Ells. 1116. Note^ on Canada, by R. W. Brock. YUKON. *260. Yukon district, by G. M. Dawson. 1887. Maps No. 274, scale 60 m. = 1 in.; Nos. 275 and 277, scale 8m. = 1 in. •295. Yukon and Mackenzie basins, by R. G. McConnell. 1889. Map No. Si\i, scale 48 m. = 1 in. (;87. Klondike gold fields (preliminary), by R. G. McConnell. 1900. Map No. e88, scale 2 m. = 1 in. 881. Klondike gold fields, by E.G. McConnell. 1901. Map No. 772, scale 2 m. = 1 in. •909. Windy Arm, Tagish lake, by R. G. McConnell. 1906. Map No. 916, stale 2 m. = 1 in. 913. Upper Stewart river, by J. Keele. Map No. 938, j scale 8 m. = 1 in. )-'RniiiiH t-nupHier 951. Peel and Wind rivers, by Chas. Camsell. Map r«ou"1 together. No. 942, scale 8 m. = 1 in. -> 979. Klondike gravels, by R. G. McConnell. Map No. 1011, s.cale 40 ch. = 1 in. 9«2. Conrad and Whitehorse mining districts, by D. D. Cairnes. 1901. Map No. 990, scale 2 m. = lin. 1016. Klondike Cre?k and Hill gravels, by R. G. McConnell. (French.) Map No. 1011, scale 40 ch. - lin. 1050 Whitehorse Copper Belt, by R. G. McConnell. Maps Nos. 1,026, 1,011, 1,044-1,019. 1097. Reconnaissance across the Mackenzie Mountains on the Pelly, Ross, and Gravel rivers, Yukon, and North West Territories, by Joseph Keele. Map No. 1099. scale 8 ni. = 1 in. 1011 Memoir No. 5 (Preliminary) : on the Lewes and Nordenskiold Rivers coal-field, Yukon, by D. D. Cairnes. Maps Nos. lift? and 1104, scale 2 m. = 1 in. BRITISH COLUMBIA. 212. The Rocky mountains (between latitudes 49° and 51° 30'), by G. M. Dawson. If85. Map No. 223, scale 6 m. = 1 in. Map No. 224. scale U m. = 1 in- •^235. Vancouver island, by G.M.Dawson. 1886. Map No. 247, scale 8 m. = 1 in. 33S. The Rocky mountains, geological structure, by R. G. McConnell. 1886. ' Map No. 248, scale 2 in. = 1 in. 263. Carilxjo mining district, by A. Bowman. 1887. Maps Nos. 278-281. •271. Mineral wealth, by G. M. Dawsnn. ' Publications marked thus are out of print. •2W. West Kootenay district, by G. M. Dawson. 1888-9. Map No. 303, scale 8 m. = 1 in. ,, ^, ,,„ , .._ •573. Kamloops district, by G. M. Dawson. 1894. Maps Nos. 556 and 557, scale 1 m. =^ 1 in. 574. Finlay and Omineca rivers, by R. G. MuGonneJl. 1894. Map No. 567, scale 8 m. = 1 in. , ,.t » « 743. Atlin Lake mining division, by J. C. Gwillim. I«fl9. Map No. 742, scale 4 m. = 1 in. 939. Roesland district, bv R. W. Brock. Map No. 941, scale 1,600 ft. =1 m. *910. Graham island, by R. W. Ells. 1905. Maps No. 921, scale 4 m. = 1 in.; No. 922, scale 1 m. = 1 in. 986. Similkameen district, by Chas. Camsell. Map No. 987, scale 400 ch. = lin. 968. Telkwa river and vicinity, by W. W. Leach. Map No. 989. sc;Ue 2 oi. = 1 in. 9%. Nanaimo and New Westminster di&tricts, by 0. E. LeRoy. 1907. Map No. 997, scale 4 m. = 1 in. 1036. Coal-6elds of Manitoba, Saskatchewan, Alberta, and Eastern British Columbia, by D. B. Dowling. 1093. Geology, and Ore' Deposits of Hedley Mining di&trict, British Colum- bia, by Charles Camsell. Maps Nos. 1095 and 1096, scale 1,000 ft. = I'in.; No. 1105, scale 600 ft. = 1 in.; No. 1106, scale 800 ft. = 1 in.; No. 1125, scale 1,000 ft. = 1 in. 1175. Memoir No. 31 : Geology and ore deposits of Phoenix, Boundary dis- trict, by 0. E. LeRoy. Map.s Nos. 1135 and 1136, scale 400 ft. = 1 in. 1204. Memoir No. 34 — E: Preliminary Report on the Clay and Shale De- posits of the Western Provinces, by Heinrich Ries and Joseph Keele. Map No. 1201-51 A, scale 3b m. = 1 in. ALBERTA. •237. Central portion, by J. B. Tyrrell. I88G. Maps Nos. 249 and 250, scale 8 m. = 1 in. 324. Peace and Athabaska Rivers district, by R. G. McConneil. 1890-1. Map No. 336, scale 48 ni. = 1 in. 703. Yellowhead Pass route, by .T. McEvoy. 1898. Map No. 676, scale 8 m. = 1 in. •949. Cascade coal-Belds, by D. B. Dowliug. Maps (8 sheets.) Nos. 929-936, scale 1 m. — 1 in. 968. Moose Mountain district, by D. D. Cairnes. Maps No. 963. scale 2 m. = 1 in. ; No. 966, scale 1 m. = 1 in. 1035. Coal-fields of Manitoba, Saskatchewan, Alberta, and Eastern British Columbia, by D. B. Dowling. Map No. 1010. scale 35 m. = lin. 1035a. French translation of coal-fields of Manitoba, Sas/katchewan, Alberta, and Eastern British Columbia, by D. B. Dowling. Map No. 1010. scale 35 m. = 1 in. 1115 Memoir No. 8-E: Edmonton coal-field, by D. B. Dowling. Maps Nos. U17-5A and 1118-6 A, scale 2610 ft. = 1 in. 1130. Memoir No. 9-E: Bighorn coal basin. Alta., by G. S. Malloch. Map No. 1132, scale 2 m. = 1 in. 1204. Memoir No. at-E : Preliminary Report on the Clay and Shale De- posits of the Western Provinces, by Heinrich Ries and Joseph Keele. Map No. 1201-51 A, scale 35 m. = 1 in. SASKATCHEWAN. 213. Cypress hills and Wood mountain, by R. G. McConnell. 1885. Maps Nos. 235 and 236, scale 8 m. = 1 in. 601 Country between Athabaska lake and Churchill river, by J. B. Tyrrell and D. B. Dowling. 1895. Map No. 957, scale 25 m. = 1 in. • Publications marked thus are out of print. 868. Souris River coal-6eld, by D. B. Dowlin?. 1902. 1035. Coal-fidds of Manitoba, Sasltatfhefwan, Alberta, and Eastern British Columbia, by D. B. Dowling. Map No. 1010. scale 35 m. = 1 in. 1201. Memoir No. 3t-E: Preliminary Report on the Clay and Shale De- posits of the Western Provinces, by Heinrich Ries and Joseph Keele. Map No. 1201-51 A, scale 35 m. = 1 in. MAJSIITOBA. 264. Duck and Riding mountains, by J. B. Tyrrell. 18S7-8. Map No. i282, scale 8 m. = 1 in. 296. Glacial Lake Agassiz, by W. Upham. 1889. Maps Nos. 314, 315, 316. 323. Northwestern portion, by J. B. Tyrrell. 1890-1. Maps Nos. 339 and 350, scale 8 m. = 1 in. 704. Lake Winnipeg (west shore), by D. B. Dowling. ~) 1898. Map No. 664, scale 8 m. = 1 in. ( -r„„„ , f„„^(.i,„.„ 705. Lake Winnipeg (east shore), by J. B. Tyrrell. ( "°^'^'^ together. 1898. Map No. 664, scale 8 ni. = 1 in. J 1035. Coal-fields of Manitoba, Saskatchewan, Alberta, and Eastern British Columbia, by D. B. Dowling. Map No. 1010, scale 35 m. = 1 in. 1201. Memoir No. 24-E: Preliminary Report on the Clay and Shale De- posits of the Western Provinces, by Heinrich Ries and Joseph Keele. Map No. 1201-51 A, scale 35 m. = 1 in. NORTH WEST TERRITORIES. 217. Hudson bay and strait, by R. Bell. 18S5. Map Nc. 229. scale 4 m. = lin. 238. Hudson bay, south of, by A. P. Low. 1886. 239. Attawapiskat and Albany rivers, by R. Bell. 1886. 244. Northern portion of the Dominion, by G. M. Dawson. 1886. Map No. 255, scale 200 ui. = 1 in. QG7. James bay and country east of Hudson bay, by A. P. Low. 578. Red lake and part of Berens river, by D. B. Dowling. 1894. Map No. 576, scale 8 ra. = 1 in. •584. Labrador peninsula, by A. P. Low. 1895. Maps Nos. 585-588, scale 25 m. = 1 in. 618. Dubawnt, Kazan, and Ferguson rivers, by J. B. Tvrrell 1896 Map No. 603, scale 35 m. = 1 in. 657. Northern portion of the Labrador peninsula, by A. P. Low 680. South Shore Hudson strait and Ungava bay. by ") A. P. Low. Map No. 699, scale 25 m. = 1 in. I o , , ,, 713. North Shore Hudson strait and Ungava bay, bv f ^°""1 together. R. Bell. Map No. 699, scale 25 m. = 1 in. J 735. Great Bear lake to Great Slave lake, by J. M. Bell. 1900. 778. East coast Hudson bay, by A. P. Low. 1900. Maps Nos. 779, 780, 781, scale 8 m. = 1 in. 796-787. Grass River region, by J. B. Tyrrell and D. B. Dowling. 1900. 815. Ebwan river and Sutton lakes, by D. R. Dowling. 1901. Map No. 751, scale 50 m. = 1 in. 819. Nastapoka islands, Hudson bay, bv A. P. Low. 1900. 905. The Cruise of the Neptune, by A."P. Low. 1905. 1003. Report of a Traver.'^.e through the Southern Part ■ of the North West Territories, from Lac Seul to Cat lake, 1902, by A. W. G. Wilson; lOSO. R«port on a Part of the North West Territories, i- Bound together. drained by the Winisk and Upper Attawa- piskat rivers, by W. Mclnnes. Map No. 1089, scale 8 m. = 1 in. 1069. French translation report on an exploration of the East coast of Hudson bay, from Cape Wolstenholme to the south end of James bay, by A. P. Low. Maps Nos. 779, 780, 781, scale 8 m. = lin.; No. 785, scale 50 m. = 1 in. ' Publications marked thus are out of print. 1097. Reconnaissance across the Maclvenzie mountains on the lelly, Ross, and Gravel rivers, Yukon, and North West Territories, by- Joseph Keele. Map No. 1099, scale 8 in. = 1 m. ONTARIO. 215. Lake of the Woods region, by A. C. Lawson. 1885. Map No. 227, scale 2'm. = 1 in. *365. Rainy Lake region, by A. C. Lawson. 1887. Map No. 2S3, scale 4. m. = 1 in. 366. Lake Superior, mines and mining, by E. D. Ingall. 1888. Maps No. 285, scale i m. = 1 in.; No. 286, scale 20 ch. = 1 m. 326. Sudbury mining district, by R. Bell. 1890-1. Map No. 343, scale 4. m. = lin. 327. Hunter island, by W. H. C. Smitfi. 1890-1. Map No. 342, scale 4 m. = 1 in. 332. Natural Gas and Petroleum, by H. P. H. Brumell. 1890-1. Maps Nos. 344-349. 357. Victoria, Peterborough, and Hastings counties, by F. U. Adams. 1892-3 . 627. On the French River sheet, by R. Bell. 1896. Map No. 570, scale 4 m. = 1 in. 678. Seine river and Lake Shebandowan map-sheets, by W. Mclnnes. 1897. Maps Nos. 589 and 560, scale 4 m. = 1 in. 723. Iron deposits along the Kingston and Pembroke railway, by E. D. Ingall. 190O. Map No. 626, scale 2m. = lin.; and plans of 13 mines. *739. Carleton, Russell, and Prescott counties, by R. W. Ells. 1899. (See No. 739, Quebec.) 741. Ottawa and vicinity, by R. W. Ells. 1900. 790. Perth sheet, by R. W. Ells. 1900. Map No. 789, scale 4 m. = 1 in. 961. Sudbury Nickel and Copper deposits, by A. E. Barlow. (Reprint). Maps Nos. 775, 820, scale Im. = lin.; Nos. 824, 835, 864, scale 400 ft. = 1 in. 962. Nipissing and Timiskaming map-sheets, by A. E. Barlow. (Re- print). Maps Nos.. 599, 606, scale 4m. = lin.; No. 944, scale 1 m. = 1 in. 966. Sudbury Nickel and Copper deposits, by A. E. Barlow. (French). 970. Report on Niagara Falls, by J. W. Spencer. Maps Nos. 926, 967. 977. Report on Pembroke sheet, by R. W. Ells. Map No. 660, scale 4 m. = lin. 980. Geological reconnaissance of a portion of Algoma ' and Thunder Bay district, Ont., by W. J. Wilson. Map No. 964, scale 8 m. = lin. 1081. On the region lying north of Lake Superior, be- [-Bound together, tween the Pic and Nipigon rivers, Qnt., by W. H. Collins. Map No. 9«4, scale 8 m. = 1 in. 992. Report on Northwestern Ontario, traversed by National Transcon- tinental railway, between Lake Nipigon and Sturgeon lake, by W. H. Collins. Man No. 993, scale 4m. = lin. 998. Report on Pembroke sheet, by R. W. Ells. (Frejich). Map No. 660, scale 4 m. = 1 in. 999. French translation Gowganda Mining Division, by W. H. Collins. Map No. 1076, scale 1 m. = 1 in. 103S. French translation report on the Transcontinental Railway location between Lake Nipigon and Sturgeon lake, by W. H. Collins. Map No. 993, scale 4 m. = 1 in. 1059. Geological reconnaissance of the region traversed by the National Transcontinental railway between Lake Nipigon and Clay lake, Ont., by W. H. Collin;:.. Map No. 993, scale 4 m. = 1 in. 1075. Gowganda Mining Division, by W. H. Collins. Map No. 1076, scale 1 m. = 1 in. ♦ Publications marked thus are out of print. 1062. Memoir No. G: Geology of tlie HaUburton and Bancroft areas, Out., by Frank D. Adams and .Alfred E. Barlow. Maps No. 708, scale 4 m. = 1 in.; No. 770, scale 2 m. = 1 in. I(i91. Memoir No. 1: On the Geology of the Nipigon basin, Ont., by A. W. G. Wilson. Map No. 1090, scale I m. = 1 in. 1114. French translation : Geological reconnaissance of ~ a porticn of Algoma and Thunder Bay dis- trict. Out., by W. .T. Wilson. Map No. 96i, scale 8 m. = 1 in. (.Bound together. 1119. French translation: On the region lying north of Lake Superior, between the Pic and Nipigon rivers, Ont., by W. H. Collins. Map No. 961, scale 8 m. = 1 in. QUEBEC. 210. Mistassini expedition, by A. P. Low. 1S81-.5. Map No. 228, scale 8 m. = 1 in. 210. C( mptrn. Stanstead. Beauce, Richmond, and Wolfe counties, by R. W. Ells. 18M. Man No. 251 (Shcrbrooke sheet), scale 4m.= 1 in. 2